1. Field of the Invention
The present invention is generally in the field of semiconductor fabrication. More specifically, the invention is in the field of fabrication of capacitors in semiconductor dies.
2. Related Art
High performance mixed signal and RF circuits require high density integrated capacitors. Metal-insulator-metal (“MIM”) capacitors can be considered for use in the fabrication of integrated mixed signal and RF circuits on semiconductor dies. In an effort to increase the capacitance density of MIM capacitors, dielectrics having a high dielectric constant (“high-k”) have been utilized in MIM capacitors. However, high-k dielectrics, such as tantalum oxide (“Ta2O5”) or hafnium oxide (“HfO2”), also tend to exhibit very high leakage current and low breakdown voltage.
In one approach to solving the problems of high leakage current and low breakdown voltage, a dielectric stack including a high-k dielectric layer situated between two cladding layers is utilized in a MIM capacitor. For example, a high-k dielectric such as Ta2O5, which has a dielectric constant (“k”) equal to approximately 25, can be situated between cladding layers comprising aluminum oxide (“Al2O3”), which has a k equal to approximately 9. The dielectric stack in the above approach achieves some reduction in leakage current and increased breakdown voltage compared to a MIM capacitor comprising a single high-k dielectric layer in a MIM capacitor.
Thus, there is a need in the art for a MIM capacitor dielectric having reduced leakage current and increased breakdown voltage.